Tainted Love
by nicole-elocin
Summary: Once I ran to you, now I'll run from you. [Maddison love affair before SGH]
1. Chapter 1

**Chapter One: Hey, Big Spender**

Author's Note: I do not own Grey's Anatomy or any of the characters.  
This takes place a longgg time before Derek moves to Seattle.

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"Derek, that's ridiculous. You don't have to stay at work, there are plenty of other surgeons in the hospital," Addison insisted, folding her arms over top of her chest. Her statement was replied with a quick roll of the eyes and slight chuckle.

"You don't understand, do you?" Derek leaned up against the wall, mirroring the same pose as his wife, arms folded together over top of his chest. "You're a gynecologist, your patients aren't as important as the ones I have." Upon hearing this, Addison couldn't stop her jaw from slightly dropping. They were both amazing surgeons, and had promised each other that they would never debate that one was better than the other.

"Yes, Derek, my patients _are_ as important. If a woman needs a C-Section, then they need me. My mistakes kill two people, your's kills one. But whatever, I'm not going to argue with you. I'm going home, so much for our double date tonight with Mark and his new girlfriend." Addison didn't wait for a response, she just walked down the narrow hallway and blinked her eyes a couple of times to force the tears to go right back in. It was idiotic, she wasn't supposed to get this offended. It was supposed to be understood that they both had jobs that were time consuming. 

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"That's not fair. He really just would rather spend time at the hospital, instead of us all having a big date?" Mark spoke in to the phone, as he tugged on a pair of boxers. His newest girlfriend, Vanessa, sat in the middle of the double bed, a bit frustrated by the fact that her boyfriend was speaking with Addison again. Vanessa didn't know much about the other girl, just that she was married and worked at the hospital. Vanessa, on the other hand, worked at a company with nothing related to medical situations or hospitals, but instead she had to deal with people who had just lost their driver's license. Yeah, no surprise that Mark wasn't picky about the women that he dated. The only thing that he had noticed about her was her body-- or more precisely, her breasts.

"Yeah, I'm sorry Mark. I'll meet her some other time, okay?" As Addison spoke to Mark, she sat at the dining room table. Her phone was pressed up against her ear with her bare shoulder, and she put a coat of pink nailpolish on her fingers. Making herself look better always made her _feel_ better, so her nails tended to change colours often.

Leaving his girlfriend in bed, Mark made his way in to the hallway. "No, Addison. I'll come over, we can have a dinner just the two of us. No, better than that, we'll have _dessert_. Your favourite ice cream is plain vanilla, isn't it?" It would have been hard for them to be friends all of those years for him not to know her favourite things.

Addison gave in, and shortly after Mark hung up, he found himself sitting on the couch in his living room with Vanessa right on top of his lap. Luckily, she had put on some clothes before going out to talk to him, so Mark would be able to control himself just a bit. Vanessa ran her hands through his hair a few times, gripping at it after a moment and pulling him in to a deep kiss. Another reason Mark liked her? It was all about touching, kissing and sex. Manwhores didn't like deep and meaningful relationships, it made them feel less... manly. To Mark, a deep relationship was as bad as getting a vasectomy-- something that he would never consider, even if he was dying of cancer.

A grin spreading his lips, Mark slid his hands down Vanessa's sides after the kiss had officially ended. "What was that about? I'm only used to you jumping me when we're out in public," he joked, beginning to tickle her sides just a bit.

A squeel escaped from the blonde's lips, and she pulled away so her 'boyfriend' could no longer touch her. "Nothing, I just wanted to make sure that you would think about me at least a bit tonight," she shrugged, pretending as if what she just said was no big deal.

"What is that supposed to mean?" The grin that had been on his face just moments ago had faded, and was replaced with an expression of pure confusion. Women were hard to understand sometimes, but Mark usually could figure out what they meant in some way. What was Vanessa implying?

"It's just... I _always_ hear you talking about Addison. You don't even talk about me," she told him, sitting down on the glass coffee table in front of Mark.

"Why in the world would I talk about you when I'm _with_ you? That doesn't make any sense. You're just insecure like all of my old girlfriends. Forget about it, okay? We were having sex ten minutes ago, I don't want to leave with you being all pissed off at me."

"Well, maybe I _am_ pissed off at you, Mark! I'm tired of the other girls flirting with you. Tell me you want to be with me."

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"Finally, you're here!" Addison exclaimed, hugging her friend tightly. "With ice cream, too. God, you're the best Mark." She took his hand, leading him in to the quiet apartment. The only sound that could be heard was the stereo in the living room playing softly. It had a CD from the early 90s playing, and the music was absolutely horrible.

Mark couldn't help but laugh, and he set the tub of ice cream down on the kitchen counter after Addison was done taking him there. "You sound kind of drunk, sweetheart," he teased, opening up the drawer and getting a spoon for him to share with Addison. He got a spoonful, and extended his arm so she could easily lick the ice cream from the spoon. After Addison cleaned the spoon, she picked up a bottle of Bailey's and poured it in to the tub of ice cream. Mark began to laugh again, taking a spoonful for himself.

"Yes, I'm drunk. Is there anything wrong with that?" she asked, hopping up to sit on the marble counter top. She swung her legs back and forth, eating the ice cream with her finger. So what if it was cold? Her finger was frozen; she couldn't feel it anyways. Mark moved to sit up on the counter as well, but he chose to use the spoon to get his ice cream.

"No, of course I don't mind you being drunk," he told her. In fact, attractive drunk women were his favourite. They were far easier to take advantage of.


	2. Chapter 2

**Chapter Two: Starts with One**

Author's Note: Sorry about not writing another chapter. Honestly, I forgot and just remembered today and decided to continue. Enjoy, and please review. I like reading comments and suggestions.

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A content sigh escaped from Addison's dry and cracked lips, nuzzling her face in to the chest of the man that lay next to her. It was late in the morning, she could tell. Even with her eyes closed, she could see the faint light coming in from the bedroom window. But she didn't want to move, it was too comfortable laying here. She ran her hands down the man's sides, moving them back up the front so her finger could trace over his bare chest, a smile spreading on her lips when she felt the sexiest abs she had ever seen or touched in her life.

This was her way of realizing it was Mark. Her nights with him were usually long and filled with alcohol, so sometimes it took her a while to remember who she was laying with. The fact that the man was naked usually indicated that it was Mark, but every now and then Derek _did_ come home and get naked with her. They just never had sex, which was disappointing. Of course, she had another way of getting sex. Maybe sleeping with her husband's best friend was low, but what was she supposed to do? Lay at home alone and have sex once a decade? She couldn't do that.

The affair had been going on for a few weeks now. They met up every other day, sometimes sneaking to the on-call room but being extra careful to lock the door. Getting caught would be deadly. They went to great lengths to make sure that Derek would never find out. Not until he was divorced from Addison, that is.

"Isn't a bit early for groping? Not that I mind..." Mark whispered, his arms wrapping around Addison's waist as he looked down at her. He had woken up an hour earlier, just to lay and watch her sleep, not wanting to risk getting up and waking her.

"Four in the morning would be early, and we're up that late anyways," she told him, voice muffled by his chest.

"Having hot, dirty, kinky..."

He was interrupted by his cell phone ringing out from it's spot on the dresser beside the bed. The ring tone was a Run DMC song, which could be considered corny, but Mark used it to know that the person calling him was someone he had previously hooked up with.

_"I met this little girlie, her hair was kinda curly  
Went to her house and bust her out, I had to leave real early  
These girls are really slea--" _the phone sang, before Mark reached over to pick it up.

"Hello?" he answered, sitting up in bed, causing Addison to open her eyes, then pout and listen careful for an indicator of who her boy toy could be talking to. "Ohhh, hey. Tonight? Sure, I'll be there. See you then," he told the person on the other side of the conversation.

Addison whined, pulling herself up to sit on his lap. She didn't want Mark going out with anyone but her, even if they weren't technically dating and there was a chance that he had only been talking to a friend. Then again, would he actually have that ring tone for a friend?

"Who was that?" she asked curiously, tracing her fingers on his arm muscles.

"Derek. He was using Dr. Cartier's phone, because his died," Mark explained.

Dr. Cartier was another attending. Sweet girl, too. Mark slept with her a few months ago, but it was nothing more than that. A shame, really.

"So, you're meeting my husband tonight? Do you think he knows?" Addison asked, a look of concern washing over her face.

Mark laughed, shaking his head. "Of course not. He may be a neurosurgeon, but he lacks common knowledge. Last week he found my boxers and thought you were just doing laundry for me."


	3. Chapter 3

**Chapter Three: Rebellion (Lies)**

Author's Note: I tried to make this chapter longer and involve Derek more. I hope you enjoy, and keep the reviews coming.

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"Mm... What's wrong?" Mark asked, pressing his lips against Addison's collar bone, leaving short kisses along it. They had a strict 'no hickeys' policy, just because they didn't want Derek to see them and get curious.

Addison snapped back to attention, looking from the spot on the wall that she had been concentrating on to Mark. "Oh, nothing," she promised.

"You're a bad liar," he told her simply, moving his kisses lower, briefly passing his lips over her breasts before kissing her stomach. "We're supposed to be having foreplay. You shouldn't be staring at a dent that we made in the wall when the bunks were over _there_."

"I'm not lying!" she insisted, her voice with a tint of a whine in it.

"And now you're lying about lying," he said, a grin spread on his face as he glanced up at her.

Addison frowned, holding herself up by leaning back on her elbows. "How would you possibly know that I'm lying?" she asked.

"You flex your left thigh," he explained, moving his hand down to grip it, but not hard enough for it to hurt her.

She snorted obnoxiously, pulling away from him and standing up from the bunks. "That makes absolutely no sense."

Mark rolled his eyes, getting up as well. He was still fully dressed except for his shirt, so he picked it up and tugged it on.

"Whatever. I have to go see your husband in a bit. I suppose it's better if I don't smell like Addison-Orgasms," he said, checking his pager.

"Orgasms? Plural? Please. You can only get one out of me when we're in here," she pointed out, beginning to pull on her clothes.

"I can get three in the on-call room. Seven at your place, six at mine," he corrected her, kissing her forehead before walking towards the door, unlocking it. "I'll call you tonight after I have drinks with Derek. Bye."

And then he left Addison, walking down the hallway so he was away from the scene of the crime and it wouldn't look suspicious when she walked out of the on-call room with her hair all messed up and her shirt on inside out.

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The bar was dimly lit, couples huddled in to their booths with colourful drinks that seemed out of place in the way-too-shady-for-rich-NYC bar. Derek sat in a free booth, downing a bottle of beer as he waited for his friend to show up. It seemed like there wasn't much time for them to hang out and actually _be_ friends anymore. To be honest, Derek cared more about his relationship with his best friend than he cared about his relationship with his wife.

Mark walked in, a look of distress and frustration on his face. He didn't know what Derek wanted with him. It sounded strange, but he wasn't used to much male bonding time lately. Ever since Mark started to sleep with Addison, he tried to avoid every situation where he had to speak to his best friend and there was no one else around to witness any possible bone smashing or stabbing if the news of the affair somehow made it's way to the oblivious neurosurgeon's ears.

"Hey," Mark breathed, sitting down across from Derek, taking the beer that he could only assume was for him.

"Hey. What's new?" Derek asked, swirling the bottle around by it's neck, which caused Mark to get nervous.

Was Derek planning to do the same thing to _him_? He hoped not.

"Nothing much," he answered, popping the top from the bottle and taking a long swig out of it.

Both of their eyes were drawn to a busty blonde who just entered the bar, wearing nothing but a short black mini dress. Both men gave a smile of approval, and Mark offered a wave to the girl. It seemed that they always had the same taste in women, which could explain why Mark was sleeping with his friend's wife.

"She's cute. Go talk to her. I don't mind," Derek insisted, setting his bottle back down on to the table.

"Oh, no. I'm... kind of seeing someone."

If Derek had been drinking something, he would have spit it all over Mark's face. Since when did Dr. Mark Sloan, infamous man whore, turn down the opportunity to flirt and possibly bed a girl, even if he was dating someone?

"You're seeing someone? And you won't cheat? My God. Who is this lucky woman?" Derek asked.

Mark swallowed, then took another long sip out of his beer to buy himself time. What was he supposed to say? Well, he'd obviously have to lie... It wasn't like he could admit that the woman he was kind-of sort-of seeing was his friend's wife, the love of both of their lives.

"You don't know her," he explained simply, frowning at his empty beer bottle.

"Is it serious?"

"I'm... not sure," Mark sighed, looking uncomfortable.

"Then go talk to that girl. If it's not serious, it shouldn't matter. There's a chance the girl you're seeing won't even find out. Go for it," Derek encouraged him.

So Mark got up, moving over to the bar where the girl was sitting on a stool. He nodded at her, then ordered himself a beer, beginning to flirt just as Derek left to go home and see his wife for once.

And when Mark went home, he wasn't alone. He had his arm around a tipsy blonde, who was eager to fall in to bed.


End file.
